The atomic-scale dynamics of a helical step emerging at the intersection of a bulk dislocation with the Ag(111) surface was studied by scanning tunnelling microscopy. The helix was found to unroll, thereby forcing a step to pass the intersection region. A coalescence event created a situation far from equilibrium, which influenced the transition of the helix towards an equilibrium structure. The evolution following the coalescence differed qualitatively from the coalescence of vacancy islands. A model was tentatively proposed, which explained the observed changes in the decay rates of the dislocation.

STM Study of Step Dynamics around a Bulk Dislocation Intersection with a Ag(111) Surface. K.Morgenstern, E.Lægsgaard, F.Besenbacher: Physical Review B, 2005, 71[15], 155426 (5pp)